Abstract
We investigated the effects of cryopreservation on CD34+ cells and aldehyde dehydrogenase (ALDH) -positive cells (ALDH (+) cells) in the umbilical cord blood (UCB) of unrelated donors. Ten units of UCB were collected at the Kanagawa Cord Blood Bank from September 2009 to November 2010. These UCB units were frozen for 2 weeks or 1 year, and then assayed for quality by flow cytometry analysis and colony-forming assay. We found that both ALDH (+) cells and the numbers of total colony-forming units and colony-forming units of granulocyte/macrophage from the isolated CD34+ cells were significantly decreased after all cryopreservation. The numbers of ALDH (+) /CD34+ cells, ALDH (+) /CD34+CD38- cells, and total colony-forming units from the cryopreserved UCB units continued to decrease over time with cryopreservation. In contrast, levels of traditional primitive surface markers were not significantly decreased in CD34+ cells and CD34+CD38- cells after cryopreservation, although this result depended on the duration of cryopreservation. These findings suggested that ALDH (+) cells could be a new marker for assessing cryopreserved UCB quality prior to hematopoietic cell transplantation.
